Emit available_externally vtables opportunistically

Summary:
We can emit vtable definition having inline function
if they are all emitted.

Reviewers: rjmccall, rsmith

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D33437

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@304394 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 34 insertions, 4 deletions

diff --git a/test/CodeGenCXX/vtable-available-externally.cpp b/test/CodeGenCXX/vtable-available-externally.cpp
index ae81959a75..db99f73d9e 100644
--- a/test/CodeGenCXX/vtable-available-externally.cpp
+++ b/test/CodeGenCXX/vtable-available-externally.cpp
@@ -12,6 +12,7 @@
 // RUN: FileCheck --check-prefix=CHECK-TEST14 %s < %t.opt
 // RUN: FileCheck --check-prefix=CHECK-TEST15 %s < %t.opt
 // RUN: FileCheck --check-prefix=CHECK-TEST16 %s < %t.opt
+// RUN: FileCheck --check-prefix=CHECK-TEST17 %s < %t.opt
 
 #include <typeinfo>
 
@@ -274,8 +275,8 @@ struct C {
   virtual D& operator=(const D&);
 };
 
-// Cannot emit B's vtable available_externally, because we cannot create
-// a reference to the inline virtual B::operator= function.
+// Cannot emit D's vtable available_externally, because we cannot create
+// a reference to the inline virtual D::operator= function.
 // CHECK-TEST11: @_ZTVN6Test111DE = external unnamed_addr constant
 struct D : C {
   virtual void key();
@@ -391,3 +392,30 @@ void test() {
 }
 }
 
+namespace Test17 {
+// This test checks if we emit vtables opportunistically.
+// CHECK-TEST17-DAG: @_ZTVN6Test171AE = available_externally
+// CHECK-TEST17-DAG: @_ZTVN6Test171BE = external
+
+struct A {
+  virtual void key();
+  virtual void bar() {}
+};
+
+// We won't gonna use deleting destructor for this type, which will disallow
+// emitting vtable as available_externally
+struct B {
+  virtual void key();
+  virtual ~B() {}
+};
+
+void testcaseA() {
+  A a;
+  a.bar(); // this forces to emit definition of bar
+}
+
+void testcaseB() {
+  B b; // This only forces emitting of complete object destructor
+}
+
+} // namespace Test17
diff --git a/test/CodeGenCXX/vtable-linkage.cpp b/test/CodeGenCXX/vtable-linkage.cpp
index c4ebf75b99..0c55eb26f7 100644
--- a/test/CodeGenCXX/vtable-linkage.cpp
+++ b/test/CodeGenCXX/vtable-linkage.cpp
@@ -145,12 +145,14 @@ void use_F() {
 // F<int> is an explicit template instantiation declaration without a
 // key function, so its vtable should have external linkage.
 // CHECK-DAG: @_ZTV1FIiE = external unnamed_addr constant
-// CHECK-OPT-DAG: @_ZTV1FIiE = external unnamed_addr constant
+// CHECK-OPT-DAG: @_ZTV1FIiE = available_externally unnamed_addr constant
 
 // E<int> is an explicit template instantiation declaration. It has a
 // key function is not instantiated, so we know that vtable definition
 // will be generated in TU where key function will be defined
-// so we can mark it as available_externally (only with optimizations)
+// so we can mark it as external (without optimizations) and
+// available_externally (with optimizations) because all of the inline
+// virtual functions have been emitted.
 // CHECK-DAG: @_ZTV1EIiE = external unnamed_addr constant
 // CHECK-OPT-DAG: @_ZTV1EIiE = available_externally unnamed_addr constant